Evony Machinery: A machine is any device that uses energy to perform some activity. In common usage, the meaning is that of a device having parts that perform or assist in performing any type of work. A simple machine is a device that transforms the direction or magnitude of a force without consuming any energy. The word "machine" is derived from the Latin machina.
Researching machinery increases the rate of wall units instantly regenerating themselves after battle. The higher level the more wall units survive. It is suggested that if the attack on you is light, the more wall units regenerate after battle. If you get attacked by an overwhelming force, less wall units will regenerate after battle.
Every single upgrade - Enhances repairable rate of fortified units by 100%